1. Field of the Invention
The present invention relates to comestible products which have been sweetened in whole or in part with L-aspartic acid derivative sweetening agents, in the presence of moisture, and more particularly to such comestible products wherein the L-aspartic acid derivatives are stabilized against decomposition during storage.
2. Description of the Prior Art
Aspartame (L-aspartyl-L-phenylalanine methyl ester) is the preferred L-aspartic acid derivative for the purposes of the present invention, and the description of the prior art, and of the present invention, will be discussed primarily based on the use of aspartame, with the understanding that the use of the other L-aspartic acid derivatives listed below is considered to the within the scope of the present invention.
Although aspartame is known to be useful as an intense or concentrated sweetening agent in various types of comestible products, its use in such products has been seriously hampered where such comestible products contain moisture, and/or where such products are manufactured in such a way as to expose the aspartame to an adverse heat history.
It is believed that the presence of water in the products and/or such heat histories leads to the rapid decomposition of the aspartame into components such as diketopiperazine which do not provide for, or detract from, the desired sweetening effect. See for example in this regard U.S. Pat. No. 4,122,195, 4,139,639, 4,384,004, and Food Engineering, B. E. Homler, May 1984, pages 127-128.
In an effort to overcome this potential decomposition problem, when using aspartame in comestible products, various solutions to the problem have been proposed. One solution is to endeavor to make the comestible products under anhydrous conditions. See in this regard, for example, International Patent Application No. W084/01693.
This procedure, of course, requires the use of stringent processing conditions in order to minimize the chances of adding moisture to the product, and it also results in severe restrictions with respect to the types and forms of raw materials that may be used. That is, it precludes the use of aqueous forms of materials such as aqueous sorbitol solutions that have been used in such comestible products with sweetening agents other than aspartame.
Another solution to the decomposition problem is to endeavor to use the aspartame in the presence of moisture but in a manner which keeps the aspartame separate and apart from the moisture. This may be done by either using the aspartame on the exterior of the comestible product, as a coating, for example, see in this regard U.S. Pat. No. 4,374,858, or by using the aspartame within the interior or bulk of the comestible product but in an encapsulated, separated, or admixed form which precludes having a significant, if any, amount of the aspartame from coming into contact with the moisture and/or an adverse heat history during the manufacture and storage of the comestible product and prior to its being ingested by the user thereof. See in this regard, for example, U.S. Pat. Nos. Re 29,682; 3,928,633; 4,122,195; 4,139,639 and 4,384,004 and Japanese Patent Application Publication No. J-58-175470, published Oct. 14, 1983 (based on Japanese Patent Application No. 57-57680 filed Apr. 7, 1982) and Japanese Patent Application Publication No. J-58-190354, published Nov. 7, 1983 (based on Japanese Patent Application No. J-57-71892 filed Apr. 28, 1982).
This latter solution to the problem, of course, requires the expenditure of significant amounts of effort and expense in pretreating the aspartame in order to effectuate the desired long term separation of the aspartame from the moisture in, and/or heat history of, the product. The encapsulating agents or other means used to effectuate this separation must also be physically and organoleptically compatible with the formulation and utility of the comestible products in which they are used.
Further, in many, if not all cases, in order to compensate for the potential loss of the aspartame during storage, even when used in conjunction with one or more of the above noted prior art solutions to the decomposition problem, it is apparently still necessary to use the aspartame at relatively high concentration levels.
Prior to the present invention, therefore, it has not been thought readily possible to provide for the use of freely dispersed aspartame, and particularly at relatively low levels thereof, in a comestible product having a relatively high moisture content and with an adverse heat history without encountering a loss of most, if not all, of its sweetening effect due to the relatively rapid decomposition of the aspartame during the storage of the comestible product under the commonly encountered shelf life conditions for such product.
An object of the present invention, therefore, is to provide a means for stabilizing aspartame against decomposition during the long term storage of comestible products containing moisture and freely dispersed aspartame, and having a heat history normally adverse to aspartame.